A combine is an agricultural vehicle used in the harvesting of crops. A forward header assembly typically is substantially wider than the aft portion of the combine and includes a plurality of spaced corn or row crop heads which are adapted for engaging the crops in removing the grain therefrom. The thus removed grain, in combination with crop residue such as husks in the case of corn harvesting, are then automatically delivered to the aft drive and processing portion of the combine which includes a complicated threshing system for further separating the grain from the crop residue and for off-loading the thus separated grain from the combine into a transport vehicle such as a truck. The crop residue is then exhausted from an aft portion of the combine and deposited in the field being harvested.
Combines typically make use of a rotating cylinder in the early stages of grain-crop residue separation. The cylinder is typically oriented horizontally and transversely to the direction of combine travel and is adapted to receive that portion of the crop which is separated from the plant by the forward header assembly. The rotating cylinder operates in cooperation with a fixed concave structure positioned adjacent to and below the cylinder. The cylinder-concave combination operates to separate the grain from the husk or leafy portion of the plant. The cylinder generally includes a first plurality of spaced raspbars around its periphery and extending the length thereof, while the concave includes a second plurality of stationary, spaced bars generally parallel to the raspbars. The crop is directed to the space between the rotating cylinder and the concave and the action of the rotating cylinder upon the crop as it is engaged by both the rotating cylinder and concave causes the grain bearing portion of the plant, i.e., the cob in corn harvesting, to become separated from the remaining portion of the plant, i.e., the leafy portion. The grain is then subjected to additional processing for further separation, while the crop residue is discharged from the combine.
The grate-like concave includes a large number of slots, or apertures, therein formed by the aforementioned second plurality of stationary, spaced bars and a plurality of concave cross bars extending between forward and aft portions of the concave. Unfortunately, the combine ingests more than just plant material. Rocks, soil and other debris taken in by the combine tend to inhibit the various threshing operations within the combine, reducing the efficiency of the grain separation process and the amount of grain recovered.
Referring to FIG. 1, there is shown a partially cutaway perspective view of a typical combine 40 which incorporates a prior art cylinder and concave arrangement. The combine 40 is comprised primarily of an aft separator/drive section 42 and a forward header assembly 50 attached to a forward portion of the separator/drive section. The separator/drive section 42 includes a cab 44 in which an operator sits and in which are positioned various operating controls for the combine. The separator/drive section 42 effects separation of the grain from the crop residue and includes a plurality of wheels 46 as well as a means for propulsion (typically a diesel engine which is not shown for simplicity) for moving the combine 40 through a field in harvesting the crops. The separator/drive section 42 includes an aft or exhaust end 42a from which the crop residue, after the grain is separated therefrom, is discharged from the combine 40 and deposited in the field being harvested.
The header assembly 50 mounted to a forward portion of the separator/drive section 42 is wider than the separator/drive section and includes a plurality of head units extending along the length thereof, such as the corn heads 52 illustrated in FIG. 1. The header assembly 50 may also be provided with a plurality of spaced row crop heads along the length thereof for harvesting soybeans, wheat, milo or rice. The corn heads 52 are adapted to separate and remove the ears of corn from the plant stalk. The grain and the plant residue are then delivered to an aft portion of the header assembly 50 and are directed to the center thereof by means of a left- and right-hand spiraled auger 54. From the center, aft portion of the header assembly 50, the grain and residue mixture is delivered to a feeder house 56 which transports the mixture via a conveyor to the combination of a rotating cylinder drum 60 and a concave screen 62. The cylinder drum 60 includes a plurality of spaced raspbars extending along the length and spaced around the periphery thereof. Rotation of the cylinder drum 60 causes the raspbars to engage the corn husks and separate the cob from the leafy portion of the plant. A beater assembly, which is not shown in the figure, is typically positioned immediately aft of the cylinder drum 60 and concave screen 62 combination for further carrying out the separation process. The beater assembly deposits the reduced mixture upon an elongated walker assembly 64 which is comprised of a plurality of vibrating sieves. The separated grain is allowed to fall through the vibrating sieves of the walker assembly 64, while the unwanted plant residue is retained on an upper portion of the walker assembly and displaced toward the rear of the combine. The thus separated grain which falls through the vibrating sieves of the walker assembly 64 is deposited upon a cleaning shoe 68 positioned below the walker assembly and comprised of a grate structure for further separating the grain from any crop residue remaining in the mixture. As the grain and residue mixture falls upon the cleaning shoe 68, a blower 66 directs an air stream on the falling mixture to remove chaff therefrom. The chaff and other crop residue removed from the mixture in the earlier separation steps are discharged from the aft or exhaust end 42a of the combine 40. The thus cleaned grain collects in a lower portion of the separator section 58 of the combine and is laterally displaced by means of a rotating clean grain auger 70 to a center portion of the combine.
The clean grain auger 70 is coupled to and continuous with a generally vertically oriented grain elevator 80. The grain elevator 80 includes a housing 82 within which is positioned a plurality of paddles 84 attached to a moving endless chain 86. The grain elevator 80 lifts individual portions of grain upward where the grain 90 is then displaced by a loading auger 88 into a storage bin or tank 92. One end of an off-loading grain drill 94 may be positioned within the storage tank 92 for removing the grain positioned therein from the combine 40.
Referring to FIG. 2, there is shown a perspective view illustrating greater details of a prior art arrangement of a feeder house 56, a concave 62, a rotating cylinder 100, a rotating beater 104, and an upper auger 106. The cylinder 100 is positioned in closely spaced relation to the concave 62 which is disposed immediately below the cylinder and comprised of a pair of curved end brackets 101 (only one of which is shown in FIG. 2 for simplicity) and a plurality of spaced bars 102 extending along the length thereof. The concave 62 further includes a plurality of spaced, curved members disposed along its length which are also not shown in the view of FIG. 2. As previously described, the combination of the rotating cylinder 100 and the concave 62 effects separation of the grain from the leafy, or husk, portion of the plant. Disposed immediately forward of the cylinder 100 is a conveyor-type feeder assembly 56 which delivers the crop directly between the cylinder and the open-mouth concave 62 as the cylinder rotates in the direction of the arrow in FIG. 2. Disposed immediately aft of the cylinder 100 is a rotating beater assembly 104 which displaces the crop material and unseparated grain from the cylinder/concave combination for further separation processing. An upper auger (not shown) disposed above and slightly forward of the cylinder 100 returns unthreshed grain which reaches the back of the cleaning area to the cylinder area for another pass between the cylinder and the concave 62.
The cylinder 100 includes a plurality of hubs, or spiders, 112 disposed in a spaced manner along the length thereof and coupled by means of an axle, or support shaft, 110 inserted through a center of each of the hubs. Each of the hubs 112 includes a plurality of spaced, upraised peripheral portions upon which are mounted raspbars 108 which extend substantially the entire length of the cylinder 100. Each of the raspbars 108 is securely mounted to an upraised peripheral portion of each of the hubs 112 in a spaced manner by conventional means such as mounting bolts or the combination of a mounting bracket and a bolt, which are not shown for simplicity.
Positioned immediately adjacent to and attached to each of the raspbars 108 along the length thereof is a respective spacer or filler plate 114. Each of the filler plates 114 extends over a portion of the gap or space between adjacent raspbars 108 and is disposed over substantially the entire length of the cylinder 100 and has a curved cross section. The filler plates 114 may be securely coupled to each of the hubs 112 by conventional means such as bolts 118.
Referring to FIG. 3, there is shown a sectional view of a portion of the prior art concave 62, rotating cylinder 100, and rotating beater 104 arrangement. As previously described, the rotating cylinder 100 includes a plurality of spaced raspbars disposed about its periphery, although only four raspbars 108a through 108d are shown in the figure for simplicity. The rotating beater 104 similarly includes a plurality of spaced wings, or extensions, 104a and 104b disposed about its periphery and extending the length thereof. The cylinder 100 as well as the beater 104 each rotate in a clockwise direction as shown by the direction of the arrows in the figure. The harvested portion of the plant including the grain and leafy portion is directed onto the lower, leading edge of the concave 62 by the combination of the rotating cylinder 100 and the previously described feeder house which is not shown in the figure. When engaged by the concave 62 as well as the raspbars disposed about the rotating cylinder 100, the grain bearing portion of the plant, such as the corncob 119 shown in the figure, is urged between the grate-like structure of the concave in a downward direction. The leafy residue of the plant is displaced rearward and upward along the upper surface of the concave 62 by the rotating raspbars of the cylinder 100. As the leafy residue arrives at the upper edge of the concave 62, it is positioned in the vicinity of the rotating beater 104 which then displaces the leafy residue rearwardly over a short flat finger grate 109. The finger grate 109 is positioned adjacent to the upper, aft edge of the concave 62 for supporting the leafy residue and maintaining it in position for rearward displacement by the rotating beater 104. After exiting the concave, cylinder, and beater assembly, the leafy residue is then further processed for the removal of additional grain therefrom and discharge from the combine.
The concave 62 includes a pair of curved brackets 101 on each end thereof. Each of the curved end brackets 101 is securely attached to a respective inner wall of the combine by means of an upper mounting bolt 103 and a lower mounting bolt 105. Extending between and mounted to each of the curved end brackets 101 are a plurality of linear, spaced crossbars 102. Each of the crossbars 102 is further coupled to a plurality of spaced, curved intermediate bars 107 along the respective lengths thereof. The combination of the crossbars 102 and curved intermediate bars 107 forms a grate like structure having a plurality of generally rectangular-shaped apertures therein.
As shown in FIG. 3, a flat finger grate 109 is disposed adjacent to the upper end of the concave 62. The flat finger grate 109 includes a plurality of spaced, elongated bars 111 extending rearward from the concave 62. The bars 111 are disposed in a spaced manner along the length of the concave 62, with their proximal ends mounted to a filler plate 117 by conventional means such as weldments. A crossbar extends between each adjacent pair of bars 111 to form the finger grate 109. Each end of the filler plate 117, which also extends along the length of the concave 62, is securely coupled to a respective mounting bracket 113. Each of the mounting brackets 113 is attached to an adjacent inner wall of the combine by means of a respective mounting pin 115. As the leafy crop residue is displaced upward by the cylinder's rotating raspbars, the finger grate 109 is intended to provide support for the crop residue as it is displaced rearward by the wings 104a, 104b of the rotating beater 104.
The spacing between the rotating cylinder and the fixed concave is critical for efficient separation of the grain and leafy portions of the plant. The prior art concave shown in FIG. 3 includes linear sections disposed adjacent to its forward and trailing edges, with a circular arcuate section disposed intermediate the leading and trailing linear sections. Adjacent to the concave's linear leading and trailing edges, the displacement between the cylinder's raspbars and the concave is greater and varies with the angular position of the raspbar. Those areas adjacent to the leading and trailing edges of the concave thus do not provide the closely spaced relation between concave and cylinder necessary for efficient threshing of the plant material ingested by the combine. In particular, with the spacing between the raspbars and the concave substantially constant in an intermediate portion of the concave and increasing near the concave's discharge end, grain not separated from the leafy portion of the plant at the intake end of the concave is not likely to be separated out so it proceeds toward the discharge end of the concave. In addition, the curved filler plates of the prior art rotating cylinder shown in FIG. 2 tend to retain the separated grain, preventing its discharge through the apertures in the concave and its separation from the leafy portion of the plant. When retained by the cylinder's curved filler plates, the grain is typically discharged rearwardly in the combine above the concave by means of the rotating beater. When discharged aft of the rotating cylinder and displaced rearwardly by the rotating beater with the leafy portion of the plant, the unseparated grain tends to be discharged from the combine into the field together with the leafy portion of the plant and is thus not recovered during harvesting. Finally, the intake end of the concave is the portion of the concave most vulnerable to damage caused by ingested non-plant debris such as rocks.
The present invention addresses and overcomes the aforementioned limitations of the prior art by providing a concave which is thicker at its leading intake end than at its aft discharge end and which is more closely spaced to its complementary rotating cylinder in proceeding toward the concave's aft discharge end for improved separation of the grain from the leafy portion of the plant. In addition, the rotating cylinder is provided with a flat, smooth outer surface between its spaced, peripheral raspbars for preventing retention of grain by the cylinder to ensure that the separated grain falls through the apertures in the concave and is recovered during harvesting.